Method of controlling electric motors.



No. 708,960. r Patented Sept. 9, I902.

J. C. HENRY, Decd.

S A HENRY EXBIMIIX METHOD OF CONTROLLING ELECTRIC MOTORS.

(Application filed. June 8, 1899.)

(Ho Mbdel.)

UNITED STATES PATENT OFFICE.

JOHN C. HENRY, OF DENVER, COLORADO; SUSIE A. HENRY, EXECUTRIX OF SAID JOHN C. HENRY, DECEASED, ASSIGNOR TO STANLEY ELECTRIC MANUFACTURING COMPANY, A CORPORATION OF NEW JERSEY.

METHOD OF CONTROLLING ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent N 0. 708,9 60, dated September 9, 1902.

Application filed June 3, 1899. Serial No. 719,264. (No model.)

To all whom, it may concern.-

Be it known that I, JOHN C. HENRY, acitizen of the United States, residing at Denver, in the county of Arapahoe, State of Colorado, have invented certain new and useful Improvements in Methods of Controlling Elec- Iric Motors, of which the following is a specification.

The apparatus herein shown for carrying out this method forms a part of my application, Serial No. 87,425, filed December 27, 1901, which is a division of this application.

The present invention is particularly intended for the controlof electric vehicles, and although many of its features are applicable to electric cars I will particularly describe it in connection with electric vehicles of the automobile type.

The invention more particularly relates to the control of a pair of dynamo-electric machines operating an electric vehicle. The machines in this case are used for propelling the vehicle and for retarding or braking the same.

In the drawings, Figure 1 represents diagrammaticallyadevelopment of my preferred form of controller, together with diagrams showing the various courses of the current through the motors, and also showing connections with the source of energy, motors, the. Fig. 2 shows in diagram the same combination as shown iii-diagram 9, Fig. 1; but in this case a special form of trolley-switch is also used therewith, whereby the motors may be short-circuited free from the line.

In Fig. 1, ARM 1 and ARM 2 represent the armature of a pair of motors, while F and F represent the fields of the motors. Trolley represents the source of energy, whether from a railway-circuit or battery, while Ground represents the other side of the circuit. The diagrams on the right-hand side of the development show the course of current when the contact-fingers are in line with the corresponding-numbered positions on the left-hand side of the development. Diagram 1, which corresponds with position No. 1, Fig. 1, shows armature No. 1 in series with its own field and field No. 2 in series with its own armature, while a cross connection of high resistance is shown between the two motors. In this combination it will be noticed the motors are disconnected from the source of energy, it being preparatory to the combination shown in diagram No. 2-1;. 6., the combinations are effected before the trolley is connected to them. In position 2, diagram 2, it will be noticed that the motors are simply series machines placed in parallel with the line, this being the starting position, and where the circuit is finally broken when stopping it is particularly desirable that the motors have great torque. At the same time the amount of current they are dealing with is very small, being limited by the high resistance of the fieldmagnets, which are ordinarily employed in shunt. The resistance forming the cross connection between the two motors is used fora double purpose. First, it offers a path for the back kick (which appears on breaking the magnetic circuit) from the low resistance armature instead of compelling it to dissipate where the resistance is very high. As the force of this kick is proportional to the resistance which it has to contend with, it is highly important in order to prevent puncturing the insulation that itis furnished with a lower resistance path or circuit. Secondly,this cross connection serves to tie the motors together, so that slipping of one and throwing of an undue proportion of the load on the other are avoided. By leaving the motors crossconnected, as shownt'. 6., the field of No. 2 in shunt with armature No. 1 and the field of No. 1 in shunt with armature No. 2the controller produces a desirable result and overcomes a defect well understood in the operation of motors for traction purposes. In the ordinary series arrangement on railway-cars, for instance, the slipping of the Wheels on one motor increases that motors speed and its voltage, and consequently robs the other motor of its voltage and force. While both motors are compelled to take the same amount of current, the slippage of one pair of wheels increases the voltage of its motor nearly equal to that of the line, so that the second motor has no forceand its wheels stand idle. By the arrangement shown the slipping of one motor increases the force of the other, so that the traction-wheels are tied, as it were, together. Bearing in mind this explanation, it will be seen how I am able in the following position-that is, in No. etto remove one motor from the circuit without sparking or flashing at the contacts or other abnormal effects. The field resistance gradually short-circuits the field of the motor No. 2, (see diagram 4,) so that the corresponding armature revolves without cutting lines of force. Its electromotive force and resistance are reduced to almost nothing. Then the armature is short-circuited, as shown in position 6, diagram 6, the field being previously short-circuited and removed by the resistance. This leaves but one motor in the circuit-t'. 6., No. 1 armature and its own field, as shown in diagram 6. In position 7 I prepare to put motor No. 2 in parallel with No. 1. I first put the field in series with the resistance across the main. (See diagram 7.) The next step, position 8, diagram 8, I connect the armature in shunt with its own field. In this position the armature being driven by the movement of the car generatesa current counter to that from the line and meets and opposes that coming from the line through the resistance, so that the current from the line and that from motor No. 2 are in opposition,and consequentlyneutralizeeach other. Consequently armature No. 2 may be connected or disconnected from the circuit without-flashing, and interruption of the circuit is avoided. In diagram 9 the motors are shown in parallel. In diagrams l0 and 11 they are also shown in parallel with resistance in their field-circuits, which regulates their speed. Diagrams l2 and 13 show means of applying the brake after the back electromotive force of the motor (owing to the slowing down of the speed) has decreased so far that it can offer no available resistance against that from the line.

In Fig. 2 means are shown whereby the supplementary or trolley switch may be used to short-circuit the motors in parallel to give a maximum braking effect.

In retracing this description it will be observed that starting with position 11, diagram l1, and moving backward I gradually increase the electromotive force of the motors, so that they regenerate current to the line or battery. The force of momentum or that of gravity is thus returned to its original source instead of being wasted by friction when slowing down, checking, or braking the vehicle.

It will he observed in position 2, diagram 2, that the amount of current absorbed by the motors is very small, owing to the higher resistance commonly used in shunt-wound mo tor-fields, so that when the circuit is broken the flash is correspondingly small. At the same time there can be no flash occasioned by the self-induction from the fields when the circuit is broken, as is usually the case in the ordinary series motors.

In position 1, diagram 1, there are two series motors in parallel with a tie including all the resistance from the leaving side of second field to entering side of first field, all connections being made excepting the open circuit at the top of contact No. 10.

In position 2, diagram 2, the connections are the same as the above, except the circuit is closed on the trolley by contact No. 10. The path of the current is then as follows: Current enters contact 10 by trolley-finger and branches, onehalf going to contact 9 via connections 10170 and via contacts 17 and 16, through armature 1, out finger l A to contact 3, thence to contact a, via connections 3, thence out finger 1 F through No. 1 field to the ground. The other half leaves contact 10, going to cont-act 5 via connections 10, 17 9, and 5, (and contacts 17, 16, and 9,) thence out finger2 I through the second field,thence to contact No. '7 via finger 2 F thence to contact 6 via connection 6, thence to armature 2 via finger 2 A, and then to the ground. The tie of resistance starts from contact 7, goes through connect-ion 7,outresistance-contact B, through five, resistance-divisions, via resistance-fingers 5, to the entering side of field I. This tie extends across from the leaving side of the 2nd. I to entering side f 1st. F.

In position 3, diagram 3, the path of the current in this position is electrically the same as in position 2, with the exception that the resistance has been decreased until its place has been taken by a conductor having no resistance, which starts at contact 8 and goes to contact 6 via connection 8, contact 7, and connection 6, thus connecting the leaving side of Ato the entering side A*. The path of the current is then through two shunt-inotors in series.

In position l, diagram 4, the current on this position enters trolley-contact 10 via trolleyfinger, divides, part going to contact 9 via connections 1O, 17', and 9, thence to A via finger 1 A, and leaves via finger 1 A going to contact 8, thence to contact (3 via connections 8 and 6", thence to second armature and ground via finger 2 A. The other part leaves contact 10, goes to contact 5 via connections 10, 1'7, 9', and 5, thence to F via finger 2 F, and then to contact 2 via finger 2 F thence to contact 4. via connections 2 and 3, thence through F to the ground via finger 1 F. The resistance (at this position is high) going around F starts at contact 10; thence through all the resistance via connection l6 and resistance-contact D and resistance-finger 6 to the leaving side of the 2d. F. via finger 1 F, contacts 4 and 3, and connections 3 and 2'.

In position 5, diagram 5, the only difference in this position from the one above is that the first field is now supplied with current direct from the trolley, as the resistance placed around F has been decreased to zero.

The current then reaches I direct from the trolley inthe following manner: In leaving the trolley-contact 10 the current goes to contact 16 via connections 10 and 17, thence to first field via finger 1 F.

Position 6, diagram 6: Armature 2 has been short-circuited, thus leaving only one motor doing work. The path of the current is as follows: The current divides at contact 10, part going to contact 9 via connections 10, 17, and 9, thence toA via finger l A, thence to the ground via finger 1 A, contact 12, and connections 12 and 11 to contact I and G finger. The other part leaving contact 10 goes to contact 16 via connections 10 and 17, thence to F and ground via finger 1 F.

Position 7, diagram 7: The path through the A and F of motor 1 is the same as previous position. Current also flows from the trolley through the resistance and F to the ground. Its path is as follows: The current leaving contact 10 goes to contact 16 via connections 10 and 17, thence through the resistance to contact 14 via finger 1 F, resistancefinger 6, thence to resistance -contact F, connections 15 and 14. From contact 14 it goes to field 2 and the ground G via finger 2 F and out by finger 2 F to contact 11, thence to ground-contact 1 via connection l1, and out G finger to ground.

In position 8, diagram 8, in addition to the paths of the current in the previous position a new one is added in this position by connecting No. 2 Arm. when the resistance has been decreased. The 2nd. Arm. gets its current from contact 15 and goes through to the ground via finger 2 A.

Position 9, diagram 9: This position is the same as the above except the field resistance has been removed, leaving two shunt-motors in parallel. The path of the current is as follows: The current divides into four branches. The first, leaving contact 10, goes to contact 9 via connections 10, 17, and 9, thence to A and ground via finger 1 A and finger 1 A to contact 12, thence throughconnections 12 11, and ground-finger G which connects with contact 1. The second branch leaves contact 10, goes to contact 17 via connection 10, thence to A and ground via finger 2 A. The third branch leaves contact 10, goes to contact 16 via connections 10 17, and thence to F and ground via finger 1 F. The fourth branch leaves contact 10, goes to contact 16 via connections 10 and 17, thence to contact 14 via finger 1 F, thence to the other finger 1 F, thence to contact 13, thence to contact 14, via connection 13, thence to F via finger 2 F, thence to ground via finger 2 F and contact 11, connection 11, contact 1, and ground-finger G.

In position 10, diagram 10, both armatures receive their current inexactly the same manner as in the previous position. The path for the fields is as follows: Current leaving the contact 10 goes through one division of resistance via connection 19, resistance-contact I, resistance-finger 1 to entering side of first field. Here it divides, part going right on through the first field to ground and the other part reaching field 2 via finger 1 F, contact 13, connection 13, contact 14, and finger 2 F. It leaves the second field by finger 2 F and gets to ground via contact 11, connection 11, and contact 1, and G finger. Position 11, diagram 11: In this position the fields take current from the trolley through the entire resistance as follows: The current leaves contact 10, goes through the resistance via connection 19, resistance-contact J, resistance-finger 6, thence to the entering side of F, from which place it follows paths exactly the same as in the previous position.-

By reference to diagrams 1 to 11 it will be seen that in all the running positions, whether the armatures are in series or in parallel with each other, the field-circuit connect-ion is always in'parallel with the armat-ures, so that any discharge-currents from the field-magnets may find a path of low resistance through the armature.

In position 13, diagram 13, (the first braking position,) the fields are excited from the trolley as follows: The trolley-current leaves contact B goes by connection B 7 to connect B thence through field F by finger 2 F and coming out through 2 F to contact 13, thence through one division of resistance via connection B 4, resistance-contact K, resistancefinger 6, through F to the ground. Both armatures are short-circuited by connections B 5 and I) 3 and contacts B B B B In this position the short-circuited armatures act as brakes for the vehicle, the efiect being limited by the resistance in the field circuit weakening the field.

Position 12, diagram 12: In this position the fields are more strongly excited, owing to most of the resistance being taken out, thus givinga stronger braking effect. The current coming to the resistance goes through resistance-finger 1, and thus through one division only. This difference in resistanceis the only change from the combination above. The armatures remain connected in the same manner as previous position.

In disconnecting a single motor from others in series I have experienced a great deal of trouble with and injury to the motors when attempting to short-circuit the armature simultaneously with or even soon after shortcircuiting the field, the trouble being caused by residual magnetism remaining in the fields after the current has ceased to fiow in the coils. In one of the best-known standard railway-motors I have found that a current away above the capacity of the armature brushes to carry would be generated from the residual magnetism in the fields alone when the former was short-circuited. In practice I was compelled with cast-iron motors to dwell about four seconds after short-circuiting the field before short-circuiting the armature, so as to give the residual magnetism time to die down. I also found by experience that where the fields were gradually shortcircnited the residual magnetism died down with a decrease of current through the coils and that the act of short-circuiting the armature may much more closely follow the shortcircuiting of the fields. It will be noticed in all of the working combinations and changes the field is maintained in parallel with a lowresistance armature.

Having thus described my invention, the following is what I claim as new therein and desire to secure by Letters Patent:

1. A method of starting a pair of motors consisting of first placing them in parallel in opposite relation to each other, each armature being in series with the corresponding field and cross-connecting them so that each armature is in shunt with the field of the other motor.

2. A method of starting a pair of motors and increasing their speed which consists in placing them in parallel in juxtaposition with each armature in series with its own field, and establishing a cross connection of high resistance between the respective armatures and fields, and then decreasing the resistance of such cross connection so that each armature will be in shunt relation to the field of the other motor.

3. A method of protecting a pair of motors from the induced current ordinarily caused by breaking of circuit, which consists in maintaining in successive running positions a short circuit between the motors, whereby the said induced current will discharge through the low-resistance armature.

4. A method of controlling electric motors, which consists in placing each armature in series with the corresponding field-magnets in separate circuits, and cross-connecting from one of such circuits to the other at points between the armatures and fields, whereby the field of each of the separate machines is connected in shunt with the armature of the other machine, substantially as and for the purpose set forth.

5. A method of regulating a pair of motors, which consists in placing the armatures in series in one circuit, and the field-magnets in series in a separate circuit, gradually shortcircuiting the field of one motor, short-cir cuiting and removing the corresponding armature, and then connecting it and its field in parallel with the armature of the other motor.

6. A method of regulating a pair of shuntmotors, which consists in connecting the armatures of said machines in series, and the fields of the machines in series, then dropping one of them from the circuit, and then connecting the armatures and fields of both motors in parallel.

7. A method of regulating a pair of motors to change the armatures from series to parallel, which consists in partially exciting the fields of a motor before placing the armature of the other motor in parallel therewith, so that the current generated by the second armature is neutralized by that from the line.

8. A method of regulating a pair of motors, which consists in first connecting them with their armatures in series and with their fieldmagnets in series, increasing the voltage of one of the motors by removing the other motor from the circuit, exciting the fields of the second motor by a connection independent of its armature and of the other first motor, and then connecting the armature of the second motor in parallel.

9. A method of regulating a pair of motors to change their armatures from series to parallel, consisting in disconnecting one of the motors from the circuit, and connecting its field and subsequently its armature in parallel with the other armature.

10. A method of varying a pair of electric motors, which consists in first connecting the motor-armatures in series, then increasing the voltage of one of the motors by decreasing the voltage of its mate, subsequently removing the latter motor, then connecting its field and afterward its armature in parallel with the field and armature of the other motor.

In testimony whereof I, the said JOHN C. HENRY, have hereunto set my hand.

JOHN C. HENRY.

Witnesses:

I. V. SIMONTON, E. F. HAYS. 

